We study the sensitivity of DESY HERA to new physics using the;helicit
y suppressed reaction e(R)p-->vX, where the final neutrino can be a st
andard model one or a heavy neutrino. The approach is model independen
t and is based on an effective Lagrangian parametrization. It is shown
that HERA will put significant bounds on the scale of new physics, th
ough, in general, these are more modest than previously thought. If de
viations from the standard model are observed in the above processes,
future colliders such as the SSC and CERN LHC will be able to directly
probe the physics responsible for these discrepancies.